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Ward Reflection Model

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jollyjeffers

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Right, it's been almost 2 weeks since I last posted a lighting model. It's almost criminal how busy I've been lately [headshake]

On the plus-side for you guys I've greatly improved the HDR Demo sample that I wrote. Look out for that in a future SDK. [wink].

In an addendum to the Oren-Nayar entry... courtesy of a PM from rollo I've realised that there the Sin()Tan() map is actually going to be essential for a ps_2_0 version. From preliminary research, the pure mathematical expansion of that term will vastly exceed the limits of a ps_2_0 profile [lol]

Ward Reflection Model

The Ward reflection model (published in the SIGGRAPH 1992 proceedings) is one of the better models for simulating metalic surfaces. It varies the specular component based on the "direction" of the surface... thus being able to mimmick brushed metallic surfaces (amongst other things)...



Inputs:
  • Diffuse Texture
  • Normal-map Texture
  • Specular-map Texture
  • ?X?Y Coefficients Texture

  • Ambient Constant
  • Light Position
  • Light Range
  • Light Falloff

  • World Matrix
  • World * View * Proj Matrix

    Vertex Data:
  • Position
  • Normal
  • Tangent
  • TexCoord

    And, as usual, a pretty Visio diagram:

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    What's the title of the shader book you mentioned a while back where you've been reading about all these lighting models? I'm rather interested in lighting models rather than the 'standard' blinn-phong one.

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    Programming Vertex and Pixel Shaders by Wolfgang Engel.

    Based on some advice, I recently ordered (got despatched today!) Advanced Lighting and Materials with Shaders by Kelly Dempski and Emmanuel Viale.

    If you're interested in the actual maths/theory of each lighting model Wolfgang Engel's book is a bit rubbish - too many typo's and mysterious name changing and so on. All of these journal entries have been started with his book, but finished by checking the actual research papers...

    Jack

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